#include <bits/stdc++.h>
using namespace std;
using T = long long;
int main() {
	int n, q;
	cin >> n >> q;
	const int S = floor(sqrt(n));  // bucket size
	const int B = (n - 1) / S + 1; // number of buckets
	vector<T> a(n), b(B);
	T sum = 0;
	for(int i = 0; i < n; ++i) {
		cin >> a[i];
		sum += a[i];
		b[i / S] += a[i];
	}
	while(q--) {
		{
			int i;
			T x;
			cin >> i >> x;
			sum += x - a[i];
			b[i / S] += x - a[i];
			a[i] = x;
			assert(sum >= 0);
		}
		if(sum == 0) {
			cout << 0 << '\n';
			continue;
		}
		int i = 0;
		T s = 0;
		while(2 * s <= sum) s += b[i++];
		assert(i > 0);
		--i;
		pair<T, int> best{numeric_limits<int>::max(), -1};
		int j = S * i - (i > 0), ls = s - b[i] - (i > 0 ? a[j] : 0);
		for(; j < min(S * (i + 1), n); ++j) {
			int rs = sum - ls - a[j];
			best   = min(best, {abs(abs(ls - rs)-a[j]%2), j});
			ls += a[j];
		}
		cout << best.second << '\n';
	}
	return 0;
}